RE: A rollback segment question on minextents

OK,

Thanks to all of you for the input.
Only if we can can have a big storage to put all the Oracle internals into our brains :)

There is a nice article in Metalink : Note 62005.1

Cheers
Kumanan

> -----Original Message-----
> From: Rachel Carmichael [SMTP:wisernet100_at_yahoo.com]
> Sent: 15 March 2002 20:59
> To: Multiple recipients of list ORACLE-L
> Subject: RE: A rollback segment question on minextents
>
> yes, Jonathan Lewis was kind enough to correct me privately on this.
>
> It is indeed only the first block that's used for header information,
> the rest of the block is used for rollback change vectors.
>
>
> --- kumanan.balasundaram_at_qxl.com wrote:
> > While on the subject..
> > Please see the Oracle Metalink Note: 1029850.6.
> > It says the first "block" of the first segment contains header
> > information.
> >
> >
> > > -----Original Message-----
> > > From: Kumanan Balasundaram
> > > Sent: 15 March 2002 17:59
> > > To: 'ORACLE-L_at_fatcity.com'
> > > Cc: 'wisernet100_at_yahoo.com'
> > > Subject: RE: A rollback segment question on minextents
> > >
> > > Oracle recommends the size NEXT=INITIAL.
> > > So if I had 10M initial, then most of the initial beyond the
> > > header info will be wasted? Sure not!
> > >
> > > Kumanan
> > >
> > > -----Original Message-----
> > > From: Rachel Carmichael [SMTP:wisernet100_at_yahoo.com]
> > > Sent: 11 March 2002 21:48
> > > To: Multiple recipients of list ORACLE-L
> > > Subject: RE: A rollback segment question on minextents
> > >
> > > the first extent is used by oracle as the segment header to manage
> > > the
> > > transaction information within the rollback segment. The second
> > > extent
> > > contains the actual change vectors
> > >
> > >
> > > --- kumanan.balasundaram_at_qxl.com wrote:
> > > > Hi,
> > > >
> > > > My point was that it could allocate one more extent as per need.
> > > Why
> > > > the
> > > > need to minextents = 2?
> > > >
> > > > Thanks
> > > > Kumanan
> > > >
> > > > > -----Original Message-----
> > > > > From: Stephane Faroult [SMTP:sfaroult_at_oriole.com]
> > > > > Sent: 07 March 2002 20:54
> > > > > To: Multiple recipients of list ORACLE-L
> > > > > Subject: Re: A rollback segment question on minextents
> > > > >
> > > > > kumanan.balasundaram_at_qxl.com wrote:
> > > > > >
> > > > > > Hi,
> > > > > >
> > > > > > I was wondering why Oracle force minextents for rollback
> > > > > > segments to be two. Why can't we have minextents zero or
> > > > > > no minextents clause at all.
> > > > > >
> > > > > > We can surely set initial extent to be large enough
> > ourselves
> > > > > > and next extent sized accordingly.
> > > > > >
> > > > > > Can someone enlighten me on the reason/thought behind this?
> > > > > >
> > > > > > Many thanks
> > > > > >
> > > > > > Kumanan Balasundaram
> > > > > > Database Administrator, IT
> > > > > > QXL ricardo plc
> > > > > > www.qxl.com
> > > > > > P: +44 (0)208 962 7409
> > > > >
> > > > > Oracle doesn't reuse an extent which contains active
> > > transactions.
> > > > What
> > > > > do you think would happen when you reach the end of your
> > initial
> > > > extent
> > > > > ? Exactly.
> > > > > --
> > > > > Regards,
> > > > >
> > > > > Stephane Faroult
> > > > > Oriole Ltd
> > > > > --
> > > > > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > > > > --
> > > > > Author: Stephane Faroult
> > > > > INET: sfaroult_at_oriole.com
> > > > >
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: 
  INET: kumanan.balasundaram_at_qxl.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
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